<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    .box-shadow {
      height: 200px;
      width: 200px;
      background: orange;
      /* 设置阴影和圆角都要用 */
      box-shadow: 0 0 10px #000;
      -webkit-box-shadow: 0 0 10px #000;
      -moz-box-shadow: 0 0 10px #000;
      -o-box-shadow: 0 0 10px #000;
      margin: 100px auto;
    }
  </style>
</head>

<body>
  <h3>阴影</h3>
  <div class="box-shadow"></div>
</body>

</html>